1. Field of the Invention
The present invention relates to an image forming device. More specifically, the present invention relates to thermal printer and image forming method that use an ink ribbon mechanism.
2. Background Information
In recent years, efforts are being made to develop image forming devices for printing print data (YMC data), which are obtained by converting and expanding image data (RGB data) from transmitted from a digital video camera. Since this kind of YMC data are structured as gradation data, it is preferable to use an image forming device that has high gradation reproducibility. Therefore, development of thermal transfer type image forming devices (thermal printers and the like) is being pursued because the gradation reproducibility of thermal transfer type image forming device is considered to be better than that of ink discharging-type image forming device.
With thermal transfer image forming devices (e.g., thermal printers), a large number of gradations can be obtained per pixel by controlling the amount of heat to be applied during printing. Thermal printers are normally provided with a thermal head (line head) having several thousand or more heating elements (dot heating elements) arranged in a row (arranged along the main scanning direction).
The thermal head is configured to transfer the dye (ink) of the ink ribbon to a transfer sheet (print sheet) by heating the ink ribbon. Since the amount of ink transferred to the print sheet varies depending on the amount of heat transferred by the thermal head, this variation is utilized to form an image having rich gradations on the print sheet.
A known image forming device is configured such that when a print driver receives a print instruction from a computer, a thermal printer application, or the like, the print driver sends a warm-up start instruction to a control unit (CPU) of the image forming device. Upon receiving the warm-up start instruction, the control unit sends a control signal to various components (e.g., the thermal head) of the image forming device and thereby starts the warm-up process. In other words, the aforementioned warm-up process is not started until after a print instruction is received from a user.
Consequently, the user is forced to wait for a period of time from when the user makes the print instruction until the printing actually starts. Furthermore, if an error occurs during the warm-up process due to, for example, the ink ribbon being expended, the time spent waiting after the user made the print instruction until the error is detected is wasted and the user may have to make the print instruction again.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for improved image forming method and image forming device that overcome the above-described problems. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.